Integrated circuit composite test generation

ABSTRACT

A chip package system comprising N multiple processor cores can be tested by receiving a data file characterizing the chip package system. Thereafter, simulation testing is conducted for each core for each of M i . . . j  states using the data file such that each core is active in each state while all other cores are inactive. Each simulation test results in a simulation. The simulations are then combined to result in a composite test covering M N*j  combinations. Related apparatus, systems, techniques and articles are also described.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/928,744, filed Mar. 22, 2018, entitled “Integrated Circuit CompositeTest Generation”, which claims priority to U.S. Provisional PatentApplication No. 62/476,347, filed Mar. 24, 2017, and U.S. ProvisionalPatent Application No. 62/615,039, filed Jan. 9, 2018, all of which areincorporated herein by reference in their entirety.

TECHNOLOGICAL FIELD

The invention resides in the field of computational integrated circuitstructure study, design, and testing.

BACKGROUND

In particular, the technological field of computational integratedcircuit study, design, and testing includes activities such as modelingof integrated circuits and the generation of tests for efficientlycharacterizing integrated circuits and to the application of tests tomodels of an integrated circuit in order to study and characterize aphysical embodiment of an integrated circuit or the behavior thereofusing a computer.

A number of methods are known for modeling and testing integratedcircuits. Computational integrated circuit studies, designs, and testsnecessarily rely on simulators. Known simulators are typically specialpurpose computers, or general purpose computers, executing specializedsoftware instructions that allow limited computer resources to addressthe highly complex calculations necessary to model an integrated circuitand simulate its behavior. These software instructions may involve manyspecific routines and shortcuts that allow the limited resources of acomputer to accurately predict the physical (e.g. electrical, thermal,mechanical, motion) behavior of physical integrated circuit components.One property of integrated circuits, the understanding of which is knownto be useful in designing and optimizing integrated circuit design ispower rail collapse, which can arise as high frequency operations createparasitic inductances in various signal paths that lead to a significantdrop in power supply voltage when switching. This in turn can causelogic errors. Because an integrated circuit, once formed, is often amonolithic device, it cannot be deconstructed to allow for invasivetesting in order to study and understand its behavior, e.g. to identifythe source of logic errors arising within it. Instead, it is onlythrough the use of simulators that an integrated circuit can be studiedand its behavior tested.

The increasing adoption of multi-core processors within integratedcircuits has, in turn, also increased the complexity of systems andtechniques for modeling such integrated circuits when they are beingdesigned. Practically speaking, the complexity of modern multicoreprocessors has rendered known modeling and testing techniquesprohibitively complicated. For example, the combination of all variousswitching scenarios for a chip package system having 8-32 centralprocessing unit (CPU) cores can require hours, and sometimes days, toprocess (thereby consuming significant computing resources). Further,known methods of identifying which testing simulation scenarios areappropriate for any given chip package configuration are often merelyguess work, thus necessitating the execution of all or numerousscenarios which are often duplicative in nature or irrelevant to the endproduct configuration. These factors increase the amount of time andresources required to prototype or otherwise characterize new integratedcircuit designs. Aside from increasing the computational power (in termsof speed, frequency, and memory sizes) only improvements to the softwaretechniques that enabling a simulator can create improvement in thistechnological field.

SUMMARY

In one aspect, a chip package system comprising N multiple processorcores can be tested by receiving a data file characterizing the chippackage system. Thereafter, simulation testing is conducted for eachcore for each of M_(i . . . j), states using the data file such thateach core is active in each state while all other cores are inactive.Each simulation test results in a simulation. The simulations are thencombined to result in a composite test covering M^(N*j) combinations.

In interrelated aspects, simulation testing includes generating acomputer readable model of the chip package system from the data file.And, applying a first set of switching combinations causing first one ormore of M_(i . . . j) states and capturing first one or more physicalcharacteristics of the behavior of the chip package in response to thefirst one or more of M_(i . . . j) states. Simulation testing also mayinclude storing the first one or more physical characteristics in a datastore. And applying a second set of switching combinations causingsecond one or more of M_(i . . . j) states and capturing second one ormore physical characteristics of the behavior of the chip package inresponse to the second one or more of M_(i . . . j) states. And storingthe second one or more physical characteristics in the data store. Thesimulation outputs may be combined to obtain a composite test coveringM^(N*j) combinations comprises:

combining one or more of the first one or more physical characteristicsof the behavior of the chip package with one or more of the second oneor more physical characteristics of the behavior of the chip package toobtain a composite test.

In embodiments, the simulations can be linearly superimposed and/ornon-linearly superimposed. And simulation testing may be conducted suchthat all N cores are inactive to result in a further simulation to formpart of the combined simulations. The simulation testing may varydifferent logic for the chip package system. The simulation testing mayrun through different switching time combinations for the chip packagesystem. The testing may result in a leakage analysis. Peak to peakvoltages and/or a level of noise may be calculated for each simulation.The multiple processor cores can form part of a single processor and/orthey can form part of two or more processors. The data file may be avalue change dump (VCD) file, a logical netlist, and/or a layout file.

In embodiments, the composite test can be executed and datacharacterizing same can be provided. The providing of data can includeat least one of: causing the data characterizing the executed compositetest in an electronic visual display, transmitting the datacharacterizing the executed composite test to a remote computing system,loading the data characterizing the executed composite test into memory,or storing the data characterizing the executed composite test intophysical data storage.

The conducted simulation testing can include testing criteria such assimultaneous switching current localization, power grid weakness,current supply congestion, or timing critical path impact, electricalconductivity to nearest package bump, power density, thermal density,change in demand current over time, component sensitivity to noise,number of logic gates, number of memory cell switching, number of cellswitching, and/or whether every block is activated.

Non-transitory computer program products (i.e., physically embodiedcomputer program products) are also described that store instructions,which when executed by one or more data processors of one or morecomputing systems, cause at least one data processor to performoperations herein. Similarly, computer systems are also described thatmay include one or more data processors and memory coupled to the one ormore data processors. The memory may temporarily or permanently storeinstructions that cause at least one processor to perform one or more ofthe operations described herein. In addition, methods can be implementedby one or more data processors either within a single computing systemor distributed among two or more computing systems. Such computingsystems can be connected and can exchange data and/or commands or otherinstructions or the like via one or more connections, including but notlimited to a connection over a network (e.g., the Internet, a wirelesswide area network, a local area network, a wide area network, a wirednetwork, or the like), via a direct connection between one or more ofthe multiple computing systems, etc.

The subject matter described herein provides many technical advantages.For example, the current subject matter enables more rapid designprototyping of integrated circuits by providing composite testing thatmore comprehensively characterize such integrated circuits.

The details of one or more variations of the subject matter describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features and advantages of the subject matter describedherein will be apparent from the description and drawings, and from theclaims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a process flow diagram illustrating the generation of acomposite test for characterizing a chip package system in accordancewith various embodiments;

FIG. 1B is a an illustration of a chip package characterization processin accordance with various embodiments.

FIG. 1C is an illustration of a modelling process in accordance withvarious embodiments.

FIG. 1D is an illustration of sub-tests in accordance with variousembodiments.

FIG. 1E illustrates aspects of composite test generation in accordancewith various embodiments.

FIG. 1F illustrates aspects of composite test generation in accordancewith various embodiments.

FIG. 2 is a diagram illustrating the results of experimental switchingcurrents in accordance with various embodiments;

FIG. 3 is a diagram illustrating results at different toggle rates;

FIG. 4 is a diagram illustrating views of simulations at a constanttoggle rate;

FIG. 5 is a diagram illustrating a view of a composite test/scenario;and

FIG. 6 is a diagram of a computing device for implementing aspectsdescribed herein.

DETAILED DESCRIPTION

The current subject matter is directed to enhanced computationalintegrated circuit simulation techniques for modeling integratedcircuits and generating simulation testing for integrated circuitsystems (referred to herein sometimes simply as “chips”) which, in turn,allow for enhanced design prototyping. In particular, applyingtechniques in accordance with this disclosure, integrated circuits, suchas CPU/GPU clusters or system on a chip (SoC) designs, can be rapidlyevaluated for thousands of switching states in a matter of minutes,where known simulators and simulation techniques can take on the orderof days. Evaluating switching states allows for voltage and currentpatterns arising from switching states to be analyzed for differentlogic and switching time combinations. The resulting evaluations areuseful for investigating integrated circuit performance outliers (e.g.,in order to check if such combinations can occur). The resultingevaluation can also be used to design mechanisms for preventingswitching combinations that generate an undesirable amount noise. Theseresulting evaluations can also be used to identifying which chip andintegrated circuit package combination drive most resonance condition.

Time domain (or transient) analyses methods have complemented and inmany cases superseded traditional static (DC) and AC (frequency domain)techniques that were considered appropriate for chip and chip-packagepower delivery network (PDN) designs; until recently these techniquesallowed sufficient study to evaluate critical criteria prior tocommitting a design for a manufacturing process. Transient simulationmethods allowed chip or chip-package-PCB engineers to model the impactof simultaneous switching current, inductance/capacitance and othertime-varying physical effects (e.g, electro-magnetic effects). With theuse of power gates, on-chip regulators, dynamic voltage scaling andother advanced techniques, transient simulations for modeling transientelectrical effects have become a critical criteria for study andsign-off prior to committing a chip package design to manufacture, orfor incorporating a chip package model into wider system study andanalysis. Prior to such commitment, studies are typically evaluated toensure that a modelled chip package does not result in violationconditions (e.g., excessive noise, over voltages, over currents, railcollapse) or logic errors.

As chip packages become increasingly more complex, transient simulationsthat attempt a full-chip analysis suffer from limitations when modelingand simulating chip behavior, and require the addition of substantialmargin in performance evaluations in order to obtain sufficientconfidence in critical criteria evaluation studies prior to commitment.As multi-core design complexity escalates, such approaches however areinherently limiting. As the number of cores is expected to continue toscale increasingly upward the critical criteria for design commitment isfundamentally different. The concerns of a package designer become lessa matter of how well the power grid is designed inside a chip package,or inside an individual CPU core, or at a higher re-distribution (RD)layer. Instead, concerns are predominantly focused on rail collapse orbounce that can happen when multiple cores are switching in differentmodes or at different times.

Critical criteria for testing may further include criteria such as:simultaneous switching current localization, power grid weakness,current supply congestion, or timing critical path impact, electricalconductivity to nearest package bump, power density, thermal density,change in demand current over time, component sensitivity to noise,number of logic gates, number of memory cell switching, number of cellswitching, or whether every block is activated.

In embodiments a mode may be a high activity mode and another mode maybe a low activity mode. In embodiments modes may be associated withdifferent switching or signal frequencies within a core. In embodimentsa first and second processor core each operate in a high activity mode,while a third and fourth process operate in a low activity mode givingrise to a first set of simulation results for an encompassing chippackage. In a second test, the first and second processor cores operatein a low activity mode while the third and fourth processors operate ina high activity mode giving rise to a second set of simulation resultsfor the encompassing chip package that is different from the first set,even though each of the processor cores themselves may be of a similardesign. It will be appreciated in embodiments there may be many modes inwhich any individual processor core may operate. It will also beappreciated that a chip package may have a different number of processorcores (e.g. in an embodiment a CPU has eight cores, and in anotherembodiment a GPU may have over 1000 processor cores in an integratedpackage. Because each processor core may execute a distinct thread, eachprocessor my operate in a particular mode at any point in time.

Based on circuit geometry, physical layout, as defined by a chippackage's architecture, and the materials and techniques involved in themanufacturing process, each processor core's mode of operation, and theparasitic effects associated with it may differ in various physicallocations across a package. For example, in embodiments a first processcore operating in an active mode may give rise to parasitic effects in afirst physical region of the chip package, while a second processor coreoperating in an active mode may give rise to different parasitic effectsin a second region, but not in the first region. The interaction ofbetween switching with a package's architecture, and parasitics, in theform of parasitic resistances, parasitics inductances, and parasiticcapacitances (RLC) dictate various phenomena within a chip package, forexample the power supply noise a package experiences. This in turndirectly affects the viable operating speeds and functional capabilitiesof a device.

To simulate multi-core switching (along with the package/PCBparasitics), existing methods cannot feasibly scale to covers theincreasingly large number of different scenarios that can exist whenattempting to evaluate every possible switching combination across eachprocessor core in a chip package (e.g. a full scale chip analysis).

Embodiments in accordance with this disclosure provide a chip-packagedesigner sufficient flexibility to allow evaluate the switching of amulti-core sub-system and its impact on the power supply without havingto perform individual time-consuming full-chip capacity scale transientsimulations for every combination of switching inputs, or everycombination of operational modes. Because of the complex electromagneticinterplay between separate signals and separate components of anintegrated circuit, seemingly small changes occurring in a firstphysical location of an integrated circuit can give rise to significantstructural and physical changes in locations of the integrated circuitthat are remote from the first location. As system operating frequenciesand signal edge rates continue to increase, signal corruption in theform of crosstalk, transients, and noise in power delivery systems arebecoming more and more limiting factors in the performance of electronicpackaging. It is physically impossible to study and evaluate thisbehavior in modern integrated circuit packages, which may involve asmany as billions of components, each of which may change state inresponse to a single signal edge propagating through the package,without the use of specialized software executing on a computerprocessing machine.

FIG. 1A-E illustrate various aspects of systems and methods forcomputational modeling of integrated circuits. FIG. 1A is a process flowdiagram 100 for generating a composite test for a chip package systemusing a computer based software simulator. Initially, at 110, a datafile, e.g. 112, is received that characterizes the chip package system,e.g. chip package 102. The data file, e.g. 112, can take various formsand be one or more of: a value change dump (VCD) file, a logicalnetlist, and/or a layout file. A data file such as data file 112 may begenerated by a characterization process, e.g. 116. Characterizationprocess 116 may be a system design software package in which a chippackage designer utilizes a CAD interface to create a computer baseddesign model of a physical chip package, e.g. 102.

In embodiments, a data file, e.g. 112, describes a system on a chip(SoC), e.g., 102, integrated with N processors (e.g. six processors 104a-104 d). In embodiments the chip package includes one or more memories,e.g. shared memory 106. The chip package may also include an I/O port,e.g. port 108, for connecting to a network, or remote data storage, orone or more additional chip packages within a wider system. Chip packagemay further include various additional circuitry or physical components,e.g. components 112, that rely on, or interact with, the N processors.Each of components of a SoC, e.g. components 104 a-d, 106, 108, 112 ofSoC 102, may communicate and route signals between various componentsacross one or more busses, e.g. bus 114.

Thereafter, at 120, simulation testing can be generated for each of Ncores for each of M_(N0 . . . Nj) states using the data file such thateach core is active in each state while all other cores are inactive, astate M_(Ni) may correspond to a particular switching combination for aparticular core. Each such simulation test results in a simulation witha simulation output. A simulation output describes the overall chippackage response in response to each state M_(Ni) of a particular corecaused by each switching combination tested. Thus in embodiments, for Ncores, a first simulation output S₀ is generated by applying statesM₀₀-M_(0j) to a first processor core. The first simulation output S₀ maybe stored in any suitable data store (e.g., memory, cache, persistentdata storage, remote data store) for later access. Then a secondsimulation output S₁ is generated by applying states M₁₀-M_(1j) to asecond processor core, and S₁ is likewise stored. This is repeated foreach processor core until a simulation S₀-S_(N) is obtained and storedfor each of the N cores.

In embodiments, simulation testing may include generating a model of thechip package system, e.g. 102. Upon receiving a data file, e.g. 112, instep 110, a modelling aspect, e.g. 138, of the software simulator maygenerate a model, e.g. computer readable model 128, of the chip packagesystem, e.g. a model of package 102, based on the data file, e.g., 112.Such a model, e.g. 128, may be held in a memory or a persistent datastore or any suitable storage, local or remote. Such a model may beconfigured to take, or be combined with, an input in the form ofswitching combinations, e.g. switching combinations input 122 a, togenerate a simulation output, e.g. simulation output 124 a, thatdescribes the behavior of model 128 in response to a set of switchinginputs, e.g. 112 a, that activate a particular process core, e.g. 104 a,to cause one or more states that correspond to a particular switchinginput.

In embodiments the switching inputs 122 a-122 d include sufficientswitching combinations to cause model 128 to experience each ofM_(N0 . . . Nj) states of a particular processor core N. An input, e.g.,122 a, may also include a set of time offsets that describe howswitching inputs are applied to a model to simulate a time varyingswitching input. In this way particular switching inputs may besimulated to occur according to various time offsets, which may giverise to additional states. Each input, e.g., 122 a, may include one ormore additional parameters. In embodiments, the additional parametersinclude an identification of which processors is targeted for switchingby corresponding switching combinations. Additional parameters mayinclude any suitable condition or additional input signals necessary oruseful for simulating behavior of model 128.

Each simulation output, e.g., simulation outputs 124 a-124 d, mayinclude, for example, a generated noise floor associated with a PDNoperating in each of one or more states arising from various switchingcombinations. Or the simulation may include an evaluation of parasitics,transients, or signal propagation timing, or over currents, arising ineach state. Alternatively, simulation output 124 a may include anencoded output describing the physical behavior of a correspondingmodeled device, e.g. the behavior of SoC 102, while a single core, e.g.104 a, is subjected to various switching combinations; such an encodedoutput may then be analyzed or studied to obtain the desired parameters(e.g., parasitics, transients, signal propagation, over currents). Inembodiments, for each switching combination provided by a simulationinput, e.g. 122 a, corresponding package behavior (e.g. currents,voltages, transients, parasitics) is generated in simulation output 124a. Thus, output 124 a may include one or more first entries describing afirst behavior in response to a first switching combination applied to afirst core 104 a. And output 124 a may include one or more secondentries describing a second behavior in response to a second switchingcombination applied to a first core, e.g. 104 a. Thus, a future analysisbased on many simulation outputs, e.g. 124 a-124 d, may selectivelycombine either a first behavior or a second behavior from a firstsimulation output, e.g., 124 a, with selected behaviors from a secondsimulation output, e.g., 124 b.

For example, FIG. 1B illustrates an exemplary SoC 102. SoC 102 includesfour processors 104 a-d, that communicate and interact with variouscircuitry 114 and memory 106 across bus 118. SoC 102 includes a port 108for external communications. SoC 102 is characterized according to acharacterization process 116 to generate a descriptive data file 112.FIG. 1C illustrates an exemplary process of receiving a descriptive datafile 112, e.g., a netlist, a VCD, or a layout file, into modeling aspect138 of a simulator software package. Modeling aspect 138 receives datafile 112 to generate a computer readable model 128 that describes SoC102. This model 128 may be stored in any suitable storage accessible bya simulator software package executing on one or more computerprocessing machines.

FIG. 1D illustrates various sub-tests, e.g. sub-tests 126 a-126 d, inaccordance with embodiments. In sub-test A, 126 a, a simulator input 122a is received and applied to model 128 to obtain simulator output 124 a.Simulator input 122 a may include various switching states. Switchinginput 122 a may include switching combinations 0-j (this is illustratedin FIG. 1D for switching input 122 a only for simplicity ofillustration, but it should be understood that each of input 122 a-122 dlikewise includes a set of switching inputs). Switching inputs 122 a-122d may include the same switching input combinations, or each may includea distinct set of switching inputs for each particular core tested.

Simulator input 122 a, as discussed above, includes switchingcombinations, timing offsets and one or more other additionalparameters. One additional parameter may include a parameter identifyinga target processor core 104 a of model 128 for switching. Thus, output124 a includes simulated device behavior responsive to the switchingcombinations, timing offsets, and other parameters of input 122 a, asapplied to core 104 a. In sub-test B, 126 b, a simulator input 122 b isreceived and applied to model 128 to obtain simulator output 124 b.Simulator input 122 b, as discussed above, includes switchingcombinations, timing offsets and one or more additional parameters. Oneadditional parameter includes a parameter targeting processor core 104 bfor switching. Thus, output 124 b includes simulated device behaviorresponsive to the switching combinations, timing offsets, and otherparameters of input 122 b, as applied to core 104 b. In sub-test C, 126c, a simulator input 122 c is received and applied to model 128 toobtain simulator output 124 c. Simulator input 122 c, as discussedabove, includes switching combinations, timing offsets and one or moreadditional parameters. One additional parameter includes a parametertargeting processor core 104 c for switching. Thus, output 124 cincludes simulated device behavior responsive to the switchingcombinations, timing offsets, and other parameters of input 122 c, asapplied to core 104 c. In sub-test D, 126 d, a simulator input 122 d isreceived and applied to model 128 to obtain simulator output 124 d.Simulator input 122 d, as discussed above, includes switchingcombinations, timing offsets and one or more additional parameters. Oneadditional parameter includes a parameter targeting processor core 104 dfor switching. Thus, output 124 d includes simulated device behaviorresponsive to the switching combinations, timing offsets, and otherparameters of input 122 d, as applied to core 104 d. In each case,simulator outputs 124 a-124 d may include a description orcharacterization of simulated behavior for each corresponding switchinginput. For example, in one embodiment, simulator output 124 a includesbehavior 0 through behavior j corresponding to input switchingcombinations 0-j. In embodiments, behaviors may include an outputsequence of time correlated data points for a plurality of physicallocations sampled throughout the SoC 102. In embodiments, these datapoints correlating to physical locations are indexed in like manner ineach of simulator outputs 124 a-124 d so as to simplify later simulationcomputations.

Later, at 130, the simulations are combined to result in a compositetest covering M^(N*j) combinations (which can later be executed). Forexample, in embodiments, the simulation outputs are combined through theprinciple of linear superposition to generate a composite test result,e.g. 132 a, as illustrated in FIG. 1E. In other exemplary embodiments,the simulation results, e.g. 124 a-124 d, are combined in a non-linearfashion. For example, a composite test result may be the result of anon-linear function F_(nl) that operates on simulation outputs, e.g. 124a-124 d, as illustrated in FIG. 1F. In embodiments, each individualrecorded behavior output from a simulation output, e.g. 124 a, may beevaluated (combined) with each recorded behavior from each othersimulation output, e.g. 124 b. Alternatively, selected behavior outputsin each simulated output may be selectively combined. For example, ifswitching combination 1 of simulation input 122 a results in a behavior2 recorded in simulation output 124 a that exceeds certain thresholds,or encounters selected conditions, behavior 2 of output 124 a alone maybe selectively combined with one or more other selected behaviorscaptured in each other simulation output, e.g. 124 b-d.

FIG. 2 is a diagram 200 illustrating two exemplary experimentalswitching scenarios, 202 and 204. In a first switching combination 202,a first modeled block is switched a single time, e.g. switching input,and a corresponding simulated voltage is measured at a particularmodeled location within a corresponding modeled chip package to obtain abehavior waveform (not particularly illustrated) in response to thatswitching current at a particular location within the tested package.For example, first switching combination may be applied to an input of afirst processor core, e.g. 104 a in a model 128 of chip package 102,causing a behavior waveform at a particular test location, e.g. testpoint 148 in a model 128 of chip package 102. This behavior waveform maybe stored as a first behavior in a simulation output data structure,e.g. 124 a. It will be appreciated that a first switching scenario mayalso include many additional switching signals occurring according toone or more time offsets, causing many additional behavior waveforms atthe tested point. It will also be appreciated that many additional testpoints may be evaluated for each input switching combination.Thereafter, in a second switching combination 204, the same block (e.g.,of processor core 104 a) is switched by repeating the same current every3.1 ns, and a second behavior response waveform (not particularlyillustrated) is generated corresponding to the same physical location inthe package, e.g. test point 148 of model 128 of chip package 102, inresponse to the second input switching combination. It will similarly beappreciated that a second switching scenario may also include manyadditional switching signals occurring according to one or more timeoffsets. The second behavior waveform is also stored in thecorresponding simulation output data structure, along with anyadditional behavior waveforms for any additional test points observed.In embodiments, many additional switching scenarios may be tested andcorresponding behavior for each scenario at each selected modeledlocation within the chip package is stored in a corresponding simulationoutput data structure.

While switching combinations may be described as one or more vectors,but there has been a move away from vector testing towards analog-based(vectorless) device-pin testing for digital devices. This trend is aresult of the difficulty in accurately and efficiently testing highspeed, low voltage, devices with vector inputs. Instead, analog openvectorless tests are relied upon to verify that a tested component doesnot suffer from structural defects. Thus, in embodiments, a switchingcombination may include a vectorless analog opens input instead ofdigital vectors as inputs.

FIG. 3 is a diagram 300 illustrating a power density map for a modeledCPU core subjected to various vectorless switching conditions. With thisarrangement, the CPU core (master) was run standalone in response tovarious vectorless conditions. Each scenario was dumped as fast signaldatabase (FSDB) to be used to drive a top level characterization. Suchan arrangement is advantageous in that it ensures all instances of themaster use the same switching scenarios. As shown in FIG. 3 , for fourscenarios subjecting the CPU core (master) to four switching conditions,four unique FSDBs were created. In embodiments the four unique FSDBs maybe four separate simulator outputs, or a single simulator output mayinclude all four unique FSDBs generated by applying the four switchingconditions to the CPU core (master). In one example, the time requiredfor this simulation was approximately 30 minutes with sixteen workersthreads were employed achieving peak memory usage of approximately 24 GBfor each worker and a resulting DB Size of approximately 99 GB.

FIG. 4 is a diagram 400 illustrating a characterization step in whicheach CPU core was simulated in the context of a four core cluster, thatis a chip package having four processor cores. For example, with ‘M’scenarios for the 4 identical blocks, 4 simulation results with Mrecorded behaviors were created (i.e., 4 cores×4 scenarios==16 behaviorsin total, stored in four simulator output structures (or alternatively,in one simulation output that is appropriately indexed for lateridentifying and retrieving desired simulation output behaviors)). Allsimulations illustrated were performed without considering leakage. Thatis no leakage was assumed. In other embodiments, particular simulationsmay obtain results for target cells in an IC package, e.g. top levelcells only. In embodiments, a leakage only mode may be evaluated toevaluate unintended power consumed by the chip package that does notcontribute to the integrated circuit chip package's desiredfunctionality. This leakage current may arise from one or moreparasitics (RLC) effects that arise in a particular switchingcombination, or one or more localized variations.

Each characterization depicted in FIG. 4 was obtained by performing asimulation of various switching combinations, each for a twenty fournanosecond duration with 50 picosecond resolution (simulation period).The eighteen analysis views were created in approximately nine hourswith 24 worker threads, with a peak memory usage of approximately 25 GBfor each worker thread, and a resulting DB size of approximately 500 GB.

FIG. 5 is a diagram 500 illustrating four combined simulated behaviorcharacterizations 502, 504, 506, 508, in which, with N cores each with Mstates, there are a total of M^(N) switching states at top level. In theexample depicted, each depicted combined simulated behavior 502, 504,506, 508 includes behavior for one of four cores that each have fourstates, resulting in 256 behaviors combined using superposition toobtain 4 combined test results. The total time to run the composite testis less than ten hours using 24 CPU cores. Also depicted is a combinedleakage test comprising leakage simulation results for each of theresulting 256 behaviors. Composite scenario 512 comprises a combinationof behavior characterizations 502, 504, 506, 508 with leakagecombination 510, illustrating

Once a composite test scenario is created, it may be stored for lateraccess or otherwise provided to an end use, where providing includes:causing the data characterizing the generated composite test in anelectronic visual display, transmitting the data characterizing thegenerated composite test to a remote computing system, loading the datacharacterizing the generated composite test into memory, or storing thedata characterizing the generated composite test into physical datastorage.

One or more aspects or features of the subject matter described hereincan be realized in digital electronic circuitry, integrated circuitry,specially designed application specific integrated circuits (ASICs),field programmable gate arrays (FPGAs) computer hardware, firmware,software, and/or combinations thereof. These various aspects or featurescan include implementation in one or more computer programs that areexecutable and/or interpretable on a programmable system including atleast one programmable processor, which can be special or generalpurpose, coupled to receive data and instructions from, and to transmitdata and instructions to, a storage system, at least one input device,and at least one output device. The programmable system or computingsystem can include clients and servers. A client and server aregenerally remote from each other and typically interact through acommunication network. The relationship of client and server arises byvirtue of computer programs running on the respective computers andhaving a client-server relationship to each other.

These computer programs, which can also be referred to as programs,software, software applications, applications, components, or code, caninclude machine instructions for a programmable processor, and/or can beimplemented in a high-level procedural language, an object-orientedprogramming language, a functional programming language, a logicalprogramming language, and/or in assembly/machine language. As usedherein, the term “machine-readable medium” refers to any computerprogram product, apparatus and/or device, such as for example magneticdiscs, optical disks, memory, and Programmable Logic Devices (PLDs),used to provide machine instructions and/or data to a programmableprocessor, including a machine-readable medium that receives machineinstructions as a machine-readable signal. The term “machine-readablesignal” refers to any signal used to provide machine instructions and/ordata to a programmable data processor. The machine-readable medium canstore such machine instructions non-transitorily, such as for example aswould a non-transient solid-state memory or a magnetic hard drive or anyequivalent storage medium. The machine-readable medium can alternativelyor additionally store such machine instructions in a transient manner,such as for example as would a processor cache or other random accessmemory associated with one or more physical processor cores.

The computer components, software modules, functions, data stores anddata structures described herein can be connected directly or indirectlyto each other in order to allow the flow of data needed for theiroperations. It is also noted that a module or processor includes but isnot limited to a unit of code that performs a software operation, andcan be implemented for example as a subroutine unit of code, or as asoftware function unit of code, or as an object (as in anobject-oriented paradigm), or as an applet, or in a computer scriptlanguage, or as another type of computer code. The software componentsand/or functionality can be located on a single computer or distributedacross multiple computers depending upon the situation at hand.

FIG. 6 is a diagram illustrating a sample computing device architecturefor implementing various aspects described herein. A bus 604 can serveas the information highway interconnecting the other illustratedcomponents of the hardware. A processing system 608 labeled CPU (centralprocessing unit) (e.g., one or more computer processors/data processorsat a given computer or at multiple computers), can perform calculationsand logic operations required to execute a program. A non-transitoryprocessor-readable storage medium, such as read only memory (ROM) 612and random access memory (RAM) 616, can be in communication with theprocessing system 608 and can include one or more programminginstructions for the operations specified here. Optionally, programinstructions can be stored on a non-transitory computer-readable storagemedium such as a magnetic disk, optical disk, recordable memory device,flash memory, or other physical storage medium.

In one example, a disk controller 648 can interface one or more optionaldisk drives to the system bus 604. These disk drives can be external orinternal floppy disk drives such as 660, external or internal CD-ROM,CD-R, CD-RW or DVD, or solid state drives such as 652, or external orinternal hard drives 656. As indicated previously, these various diskdrives 652, 656, 660 and disk controllers are optional devices. Thesystem bus 604 can also include at least one communication port 620 toallow for communication with external devices either physicallyconnected to the computing system or available externally through awired or wireless network. In some cases, the communication port 620includes or otherwise comprises a network interface.

To provide for interaction with a user, the subject matter describedherein can be implemented on a computing device having a display device640 (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display)monitor) for displaying information obtained from the bus 604 to theuser and an input device 632 such as keyboard and/or a pointing device(e.g., a mouse or a trackball) and/or a touchscreen by which the usercan provide input to the computer. Other kinds of devices can be used toprovide for interaction with a user as well; for example, feedbackprovided to the user can be any form of sensory feedback (e.g., visualfeedback, auditory feedback by way of a microphone 636, or tactilefeedback); and input from the user can be received in any form,including acoustic, speech, or tactile input. In the input device 632and the microphone 636 can be coupled to and convey information via thebus 604 by way of an input device interface 628. Other computingdevices, such as dedicated servers, can omit one or more of the display640 and display interface 624, the input device 632, the microphone 636,and input device interface 628.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” can occur followed by a conjunctive list ofelements or features. The term “and/or” can also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it is used, such a phrase isintended to mean any of the listed elements or features individually orany of the recited elements or features in combination with any of theother recited elements or features. For example, the phrases “at leastone of A and B;” “one or more of A and B;” and “A and/or B” are eachintended to mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” In addition, use of the term “based on,” aboveand in the claims is intended to mean, “based at least in part on,” suchthat an unrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems,apparatus, methods, and/or articles depending on the desiredconfiguration. The implementations set forth in the foregoingdescription do not represent all implementations consistent with thesubject matter described herein. Instead, they are merely some examplesconsistent with aspects related to the described subject matter.Although a few variations have been described in detail above, othermodifications or additions are possible. In particular, further featuresand/or variations can be provided in addition to those set forth herein.For example, the implementations described above can be directed tovarious combinations and subcombinations of the disclosed featuresand/or combinations and subcombinations of several further featuresdisclosed above. In addition, the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. Other implementations may be within the scope of the followingclaims.

What is claimed is:
 1. A method for testing a chip package systemcomprising N processor cores, the method comprising: receiving a datafile characterizing the chip package system, the N processor coresincluding a first processor core and a second processor core; applying afirst set of switching combinations to the first processor core causinga first number of states and capturing first one or more physicalcharacteristics of behavior of the chip package system in response tothe first number of states, wherein the first number of statescorresponds to a total number of different states on which the firstprocessor core is tested; applying a second set of switchingcombinations to the second processor core; causing a second number ofstates and capturing second one or more physical characteristics of thebehavior of the chip package system in response to the second number ofstates, wherein the second number of states corresponds to a totalnumber of different states on which the second processor core is tested;and combining one or more of the first one or more physicalcharacteristics of the behavior of the chip package system with one ormore of the second one or more physical characteristics of the behaviorof the chip package system to obtain a composite test.
 2. The method ofclaim 1, further comprising: generating a computer readable model of thechip package system from the data file; storing the first one or morephysical characteristics in a data store; storing the second one or morephysical characteristics in the data store.
 3. The method of claim 1,wherein the one or more of the first one or more physicalcharacteristics and the one or more of the second one or more physicalcharacteristics are linearly superimposed or non-linearly combined. 4.The method of claim 1 further comprising: conducting simulation testingsuch that all N cores are inactive to result in a further simulation toform part of combined simulations.
 5. The method of claim 1, wherein thesimulation testing varies different logic for the chip package systemand includes at least one leakage analysis.
 6. The method of claim 1,wherein the simulation testing runs through different switching timecombinations for the chip package system.
 7. The method of claim 1further comprising: calculating peak to peak voltages for eachsimulation.
 8. The method of claim 1 further comprising: determining foreach core a level of noise associated with each of a plurality ofstates.
 9. The method of claim 1, wherein the multiple processor coresform part of a single processor.
 10. The method of claim 1, wherein themultiple processor cores form part of two or more processors.
 11. Themethod of claim 1, wherein the multiple processor cores form part of achip package system.
 12. The method of claim 1, wherein the data file isa value change dump (VCD) file, a logical netlist, or a layout file. 13.The method of claim 1 further comprising generating a composite test byselectively combining portions of each simulation output.
 14. The methodof claim 13 further comprising: providing data characterizing thegenerated composite test.
 15. The method of claim 14, wherein theproviding data comprises at least one of: causing the datacharacterizing the generated composite test in an electronic visualdisplay, transmitting the data characterizing the generated compositetest to a remote computing system, loading the data characterizing thegenerated composite test into memory, or storing the data characterizingthe generated composite test into physical data storage.
 16. The methodof claim 1, further comprising: generating simulation outputs comprisingsimulated behaviors associated with criteria selected from a groupconsisting of: simultaneous switching current localization, power gridweakness, current supply congestion, or timing critical path impact,electrical conductivity to nearest package bump, power density, thermaldensity, change in demand current over time, component sensitivity tonoise, number of logic gates, number of memory cell switching, number ofcell switching, or whether every block is activated.
 17. A system fortesting a chip package system comprising N processor cores comprising:at least one data processor; and memory storing instructions which, whenexecuted by the at least one data processor, cause the at least one dataprocessor to: receive a data file characterizing the chip packagesystem, the N processor cores including a first processor core and asecond processor core; apply a first set of switching combinations tothe first processor core causing a first number of states and capturingfirst one or more physical characteristics of behavior of the chippackage system in response to the first number of states, wherein thefirst number of states corresponds to a total number of different stateson which the first processor core is tested; apply a second set ofswitching combinations to the second processor core; causing a secondnumber of states and capturing second one or more physicalcharacteristics of the behavior of the chip package system in responseto the second number of states, wherein the second number of statescorresponds to a total number of different states on which the secondprocessor core is tested; and combine one or more of the first one ormore physical characteristics of the behavior of the chip package systemwith one or more of the second one or more physical characteristics ofthe behavior of the chip package system to obtain a composite test. 18.The system of claim 17, wherein when executed the instructions furthercause the at least one data processor to: generate a computer readablemodel of the chip package system from the data file; store the first oneor more physical characteristics in a data store; and store the secondone or more physical characteristics in the data store.
 19. Anon-transitory computer program product for testing a chip packagesystem comprising N processor cores, the non-transitory computer programproduct storing instructions which, when executed by at least one dataprocessor forming part of at least one computing device, cause the atleast one computing device to: receive a data file characterizing thechip package system, the N processor cores including a first processorcore and a second processor core; apply a first set of switchingcombinations to the first processor core causing a first number ofstates and capturing first one or more physical characteristics of thebehavior of the chip package system in response to the first number ofstates, wherein the first number of states corresponds to a total numberof different states on which the first processor core is tested; andapply a second set of switching combinations to the second processorcore; causing a second number of states and capturing second one or morephysical characteristics of the behavior of the chip package system inresponse to the second number of states, wherein the second number ofstates corresponds to a total number of different states on which thesecond processor core is tested; and combine one or more of the firstone or more physical characteristics of the behavior of the chip packagesystem with one or more of the second one or more physicalcharacteristics of the behavior of the chip package system to obtain acomposite test.
 20. The non-transitory computer program product of claim19, wherein the instructions, when executed, further cause the at leastone computing device to: generate a computer readable model of the chippackage system from the data file; store the first one or more physicalcharacteristics in a data store; and store the second one or morephysical characteristics in the data store.